The present invention relates to an improved hole opener for use in increasing the diameter of holes in drilling and more specifically, to a hole opener having a set of arms that may be changed to increase the size of the cutter allowed to be used so that a variety of different sized holes might be drilled using the same hole opener body.
In the drilling industry, whether for exploration of oil and gas, mining, water well development or the like, an operator may desire to widen the existing diameter of a hole previously drilled. A number of prior art devices have been used for enlarging such holes. Most hole openers currently in use provide a fixed-arm arrangement which supports a pin through the cutter shell and are prone to failure when excessive wear allows the arm to fail and the pin to collapse, with the possibility that such devices might then be stuck in the hole, necessitating an expensive retrieval job.
The present invention provides a tubular body with threaded connections at either or both ends to enable connection in a drill string, and further providing a passage therethrough for the passage of drilling fluid, including air. The tubular body supports a plurality of detachable support arms for each cutter which are bolted, pinned, or otherwise removably attached to the tubular body and which engage the outer or distal end of a journal body. The journal body is engaged at its proximal end on a spindle providing an eccentric or otherwise non-circular profile so that the journal cannot be rotated on the spindle. Alternatively, the spindles may also be recessed in the tubular body providing additional structural support for the journals, and further providing a restraint to movement of the journal on the spindle. The journal provides bearings to facilitate rotation of a cutter on the journal. The cutter shell is carried on the journal body and eliminates the customary pin arrangement through the axis of rotation of the cutter body, which was used to support all known prior art hole openers. A pressure compensated means of lubricating the bearings on the journal is also provided thereby increasing the life of the bearings and the useful life of the hole opener.